Production of organic compounds from methane sulfonic acid



i atenteci May 2 ,553,576 7 M bromine. COMPOUNDS FROM METHANE soL'Fomc ACID Aiji'soa v, o s'se; Haverford, and John 0; Snyder; Darlington, Pa;,:as"signors to Houdry Process Corporation, Wilmington, Del., a corporation of Delaware o firawii i fi. zjip plication March 26, 1947,

Serial N0. 737,408

i0 oaths. (01. 260-152;)

This invention renter: to processes for the deposition Of fnethane 'sulfonic acid and t0 the products formed thereby. This application .is a EofitihuatitSn-in-part or our co-pending applica-'- tion, serial No. evaczamea May 31, 1946, now Patent No; 2,492,983, issued on January 3, 1950. In our pending application we have disclosed that by subjecting methane sulfonic acid to elevs ed temperatures; such as temperatures in the range of 225" to 500 'C.,the methane sulfonic acid is decomposed and sulfur dioxide and methanol; free or combined form, are among the products of decomposition. The present invention is based on the discovery that the decomposition or pyrolysis of methane sulfonic acid can be met ated by carrying out the reaction in" the pre eats of a methane sulfo'nateof a metal below (and not including) ma nesium in the electromotive serie'sof metals (as set forth at he bottom of page 1074 o f the sixth edition or Ha te of fie h li Pu s e s; Incl, Sandusky, Ohio, 19 metals have moderate Io Weahbase yfiirfmng j pert and are exemplif e by he s 11mm, silvr,' thoriu'mg ercu'ry the '1' r s, bismuth, lead;iron, th e over, we have foundthat methane s v can be decomposed so that one or info edemativ's of methanol, such as in 1r1ethane t V g I I .iq m methyl mle h n H simple riletlifod' for gobtainmgea compo 1 A We prefer. to use the methane sulfonic acidinuthe. free state exceptinsofar ,as itmayrcactpwith compounds of metals added to accelerate the do; composition .as described herein; and any event, the acid should-not be in the form oi an alkali metal salt since the controlled decomposition of the alkali smetal salt to form methanol and derivatives of methanol is difficult if not impossible. t r r r r, As ,disciosedin our prior application, thether: ni'al decomposition may be effectedr'at preferred temperatures in the range mentioned above, an especially suitable temperature"beingabout 325 C., as'by refiuxingthe free methanesulfonic acid at atmospheric pressures. In performing therefluxing operation, aninert gas such as nitrogen, hydrogen, carbon dioxide or the like may be used to sweep out the methanol and sulfur dioxide or other reaction products,.or the temperature of the condenser or dephlegmator may be adjusted to allow these products to pass overhead. When a portionof the methanol produced reacts with the undecomposed methanev sulfonic acid to form an ester, a fraction composed principally of. the ester may be obtained bycarrying the decomposition reaction substantially to com-plea tionor by separating the esterwand the free methanessulfonic acid, as, by distillation. 911: methanol is desired as the final. product, the

' ester can then be easily hydrolyzed to obtain methanol and the free acid, which may then (be subjected to decomposition to produce additional methanol or. the ester may be both hydrolyzed and the free acid decomposed in the same operation as described below. The process may also be carried out bypassing the methane sulfonic acid through a decomposition. zone, .suchas a tube either empty orv fillednwith an inert mate;- rial for. heat capacity. .This zone is held at a suitable temperature Within a preferred range. of 300 to 400 C. The methane sulfonic acid may be injected into the reaction zone as a liquid or may enter the reaction zone as a vapor, either alone or in conjunction with an inert gas. In the thermal decomposition process of our pending application, dimethyl ether may be among the reaction products. i

In accordance with the present invention, we accelerate the formation of methanol andmr derivatives of methanol, such as dim'eth'yl other and methyl methane sulfona'te, irom methane sulfonic acid by subjecting 'm'etlian'e sulfonic acid to pyrolysis at' elevated temperatures selectedlto promote the removal or sulfur dioxide from methane sulfo'riic acid, such as temperatures ittasv ate the decomposition of the methane sulfonic 7 carrier, such as silica gel, pumice, or kieselguhr, j

and thereafter contacted with the methane sulfonic acid in the vapor state. ple, the compound of the metal may be an oxide, hydroxide, or hydrous oxide or a salt having an anion, such as a carbonate or a sulfide, which produces a gas when the salt reacts with the free methane sulfonic acid. Alternatively, the compound of the metal may be a salt having an anion which is substantially unreactive when dissolved or suspended in the methane sulfonic acid, such as sulfate, phosphate, or borate. The compound of the metal may have an anion which forms, by interaction with the methane sulfonic acid, a distillable liquid, such as acetate or similar organic anions. Any of the above compounds may be used to impregnate an inert carrier, preferably porous, and the impregnated carrier thereafter contacted with methane sulfonic acid, preferably in the vapor phase. Alternatively, the compound of the metal may be a colloidal gel, such as alumina gel, associated with another colloidal gel in a contact mass such as a silicaalumina gel. In general, the amount of the compound of the metal employed is less than that equivalent to one mole of the metallic element to six moles of methane sulfonic acid, while amounts as low as those equivalent to one mole of the metallic element to 500 moles of methane sulfonic acid have been found effective.

-: Water, preferably in the form of steam, may be used with the methane sulfonic acid to aid the decomposition or pyrolysis process, particularly when methanol is the desired product. When water is present during the pyrolysis, the methane sulfonic acid can conveniently contain the methyl ester thereof (CHsSOsCI-Iz), particularly when the methane sulfonic acid is, at least in part, derived from the sulfonation of methane. In a continuous process such as described above, the methyl ester may be added separately to the reaction zone, in which event, water or steam may be added to the methyl ester before it enters the zone. Such mixtures of methyl methane sulfonate and water may be preheated to aid the hydrolysis of the ester. The methyl methane sulfonate is easily hydrolyzed and thus it furnishes additional quantities of methanol and methane sulfonic acid when added to a reaction zone in V which methane sulfonic acid is being thermally decomposed to methanol in the presence of steam. When mono-sulfonated derivatives of methane, such as either methane sulfonic acid or its methyl ester or both, are charged to the thermal decomposition zone, the effluent mixture therefrom may be cooled to a temperature somewhat above the boiling point of methanol, such as about 100 C., in order to condense any unconverted methane sulfonic acid or any high Thus, for examboiling material present or' formed in the proc-* ess, the cooled vapors separated and the methanol, lower boiling organic products, and sulfur dioxide recovered.

We obtain derivatives of methanol, such as methyl methane sulfonate or dimethyl ether or both, by subjecting methane sulfonic acid to pyrolysis conditions in the presence of a catalyst as herein described and thereafter separating at least one of such derivatives from the resultant products. The yield of such derivatives of methanol may be increased by increasing the time of contact of the methane sulfonic acid and the methanol liberated in the decomposition. Thus we may reflux methane sulfonic acid, at atmospheric pressure, to which acid a compound of a metal may be added to accelerate the decomposition as described above, under dephlegmating conditions-such that any methyl methane sulfonate formed distills over and thereafter separate the distillate into fractions by further distillation, extraction or other methods known to the art and thus obtain fractions consisting of methanol or one of its derivatives, methyl methane sulfonate or dimethyl ether. Alternatively, we may employ a distillation column from which methyl methane sulfonate is taken off as a side stream and any methanol formed is totally refluxed. When it is desired to increase the yield of dimethyl ether, dephlegmating conditions may be maintained so as to retain as much as possible of the methyl methane sulfonate in the decomposition zone. Alternatively, any methyl methane sulfonate in the distillate may be recycled to the decomposition zone.

In order to illustrate the present invention but not to be construed as a limitation thereof, the following examples are given:

Example I (A) Methane sulfonic acid was refluxed for four hours at about 310 C. under heating and dephlegmating conditions such that the vapors which distilled over were at a temperature slightly below 250 C. The distilled vapors were passed first through an ice cooled trap and then through a trap cooled with solid carbon dioxide from which sulfur dioxide was recovered.

The material collected in the ice cooled trap was liquid and formed two layers. This material, on distillation and drying, yielded some undecomposed methane sulfonic acid (estimated to be about 12% of the original acid) and an amount of methyl methane sulfonate equivalent to about 31% of the original acid (based on conversion of two moles of the acid to one mole of ester).

Distillation of the residue of the refluxing operation yielded pure methane sulfonic acid (about 56% of the original acid) and a carbon residue equivalent to less than 1% of the original acid.

(B) Methane sulfonic acid was heated with silver carbonate (0.045 mole of AgzCOs per mole of acid) until the latter dissolved and evolution of carbon dioxide ceased. The resultant solution which was clear, was refluxed for 1.25 hours under conditions similar to those described under (A).

Examination of the residue and products indicated that the reaction products consisted predominately, if not completely, of methyl methane sulfonate. This ester saponified readily with sodium hydroxide to yield methanol. The amount of the methyl methane sulfonate recovered was equivalent to about 49% of the original acid.

Comparison of the above results with those set forth under (A) shows that the metal compound present accelerated the reaction, giving a higher yield in a shorter time.

Example II Methane sulfonic acid and finely ground aluminum oxide (0.013 mole of A1203 per mole of acid) were subjected to refluxing for 0.5 hour under the same conditions as in Example I (B), during which time about half of the aluminum oxide dissolved. About 16% of the acid was converted to ester.

Example III Methane sulfonic acid and bismuth subcarbonate (0.0023 mole of Bi2O3'CO2'I-I2O per mole of acid) were initially heated until a clear solution resulted and the evolution of carbon dioxide ceased. The clear solution was subjected to refluxing under the same conditions as in Example I (B) for 1.33 hours during which time methyl methane sulfonate was formed in an amount equivalent to about 45% of the original acid with V the simultaneous evolution of sulfur dioxide in an amount equivalent to a little over 50% decomposition.

Example IV Methane sulfonic acid was refluxed for four hours at about 300 to 310 C. in equipment which provided fractionation of the evolved vapors, by placing a column '75 mm. high filled with glass helices above the vessel in which the acid was heated. The temperature of the distillate removed from the top of the fractionating column was maintained at about 100 C. The distillate was collected as in Example I. About 43% of the acid decomposed under these conditions. Separation and analysis of the various fractions and the residue showed that, based on 100% decomposition of the acid, the following products are formed:

Percent Methyl methane sulfonate 43 Dimethyl ether 35 Methanol Carbonaceous material 2.2

Additional runs using similar conditions to those given above, demonstrated that either mercuric oxide or thorium dioxide accelerated the decomposition.

. Obviously many modifications and variations of the invention as hereinbefore set forth may be made without departing from the spirit and scope thereof and. therefore only such limitations should be imposed as are indicated in the appended claims.

We claim as our invention:

1. The process which comprises thermally decomposing methane sulfonic acid in the free state and in the presence of a small quantity, sufficient to catalyze the decomposition, of a methane sulfonate of a metal below magnesium in the electromotive series of metals at a temperature of at least 225 C. and below 500 C. in a decomposition zone to form decomposition products comprising at least one compound selected from the group consisting of methanol, dimethyl ether and methyl methane sulfonate and removing said decomposition products from the decomposition zone.

2. The process which comprises thermally decomposing methane sulfonic acid in the free state and in the presence of a small quantity, sufficient to catalyze the decomposition, of a methane sul- O fonate of a metal below magnesium in the electromotive series of metals at a temperature of at least 300 C. and below 400 C. in a decomposition zone to form decomposition products comprising at least one compound selected from the group consisting of methanol, dimethyl ether and methyl methane sulfonate and removing said decomposition products from the decomposition zone.

3. The process which comprises thermally decomposing methane sulfonic acid in the free state and in the presence of a small quantity, sufficient to catalyze the decomposition, of a methane sulfonate of a metal below magnesium in the electromotive series of metals in a decomposition zone to form decomposition products comprising at least one compound selected from the group consisting of methanol, dimethyl ether and methyl methane sulfonate, removing said decomposition products from the decomposition zone and separating at least one compound selected from the group consisting of methanol, dimethyl ether and methyl methane sulfonate from said decomposition products.

4. The process of claim 3 wherein the metal is aluminum.

5. The process of claim 3 wherein the metal is bismuth.

6. The process of claim 3 is mercury.

7. The process which comprises thermally decomposing methane sulfonic acid in the free state and in the presence or" a small quantity, sufficient to catalyze the decomposition, of a methane sulfonate of a metal below magnesium in the electromotive series of metals in a decomposition zone to form decomposition products comprising dimethyl ether, removing said decomposition products from the decomposition zone and separating dimethyl ether from said decomposition products.

8. The process of claim '7 wherein the metal is mercury.

9. The process which comprises thermally decomposing methane sulfonic acid in the free state and in the presence of a small quantity, suflicient to catalyze the decomposition, of a methane sulfonate of a metal below magnesium in the electromotive series of metals in a decomposition zone to form decomposition products comprising methyl methane sulfonate, removing said decomposition products from the decomposition zone and separating methyl methane sulfonate from said decomposition products.

10. The process of claim 9 wherein the metal is mercury.

wherein the metal ARISTID V. GROSSE. JOHN C. SNYDER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,492,983 Grosse et a1 Jan. 3, 1950 2,493,038 Snyder et a1 Jan. 3, 1950 OTHER REFERENCES Billeter, Ber. Deutsch chem. Ges., vol. 38 (1905) page 2019.

Williams, J our. Am. Chem. $00., vol. 53 (1931) pages 3407 to 3413.

Hurd, Pyrolysis of Carbon Compounds, 1929, page 706. 

1. THE PROCESS WHICH COMPRISES THERMALLY DECOMPOSING METHANE SULFONIC ACID IN THE FREE STATE AND IN THE PRESENCE OF A SMALL QUANTITY, SUFFICIENT TO CATALYZE THE DECOMPOSITION, OF A METHANE SULFONATE OF A METAL BELOW MAGNESIUM IN THE ELECTROMOTIVE SERIES OF METALS AT A TEMPERATURE OF AT LEAST 225* C. AND BELOW 500* C. IN A DECOMPOSITION ZONE TO FORM DECOMPOSITION PRODUCTS COMPRISING AT LEAST ONE COMPOUND SELECTED FROM THE GROUP CONSISTING OF METHANOL, DIMETHYL ETHER AND METHYL METHANE SULFONATE AND REMOVING SAID DECOMPOSITION PRODUCTS FROM THE DECOMPOSITION ZONE. 